Child and adolescent psychiatry: Lesch-Nyhan syndrome: practice question

A Psychiatry question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Psychiatry · Child and adolescent psychiatry: Lesch-Nyhan syndrome

Sample item

A 3-year-old boy has developmental delay, dystonia and choreoathetosis, and repeatedly bites his lips and fingers. His diapers show orange crystals and serum uric acid is high. Which disorder is this?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. Lesch-Nyhan syndrome

Lesch-Nyhan syndrome is an X-linked recessive disorder of purine metabolism caused by HGPRT deficiency. It causes hyperuricaemia, intellectual disability, dystonia and compulsive self-mutilation, mostly biting of lips and fingers, in boys.

Option by option

  • A. Prader-Willi syndrome

    Prader-Willi syndrome causes hypotonia, hyperphagia, obesity and hypogonadism.

  • B. Rett syndrome

    Rett syndrome affects girls with regression of hand skills and stereotyped hand-wringing.

  • C. Lesch-Nyhan syndrome (correct)

    Correct. Self-biting with hyperuricaemia and dystonia indicates HGPRT deficiency.

  • D. Fragile X syndrome

    Fragile X syndrome causes intellectual disability, large ears, macro-orchidism and autistic features, without hyperuricaemia.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Psychiatry question

What is the answer to this Psychiatry question?

The best answer is C, Lesch-Nyhan syndrome. Lesch-Nyhan syndrome is an X-linked recessive disorder of purine metabolism caused by HGPRT deficiency.

Why is "Prader-Willi syndrome" not the answer?

Prader-Willi syndrome causes hypotonia, hyperphagia, obesity and hypogonadism.

Why is "Rett syndrome" not the answer?

Rett syndrome affects girls with regression of hand skills and stereotyped hand-wringing.

Why is "Fragile X syndrome" not the answer?

Fragile X syndrome causes intellectual disability, large ears, macro-orchidism and autistic features, without hyperuricaemia.

What concept does this question test?

It tests Child and adolescent psychiatry: Lesch-Nyhan syndrome in Psychiatry. It causes hyperuricaemia, intellectual disability, dystonia and compulsive self-mutilation, mostly biting of lips and fingers, in boys.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Child and adolescent psychiatry: Lesch-Nyhan syndrome?

Learn each diagnosis by its core features and its first-line treatment. Then use the flashcards and the other Psychiatry questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.